6.5 Building Commissioning

Building Commissioning (Cx) is an exhaustive quality assurance process intended to bridge the gap between design, construction, and operations. According to ASHRAE (the leading authority on building systems), commissioning is a quality-focused process for enhancing the delivery of a project by verifying and documenting that all of the commissioned systems and assemblies are planned, designed, installed, tested, operated, and maintained to meet the Owner's Project Requirements (OPR).

While traditional QC inspections verify that a single piece of equipment (e.g., a chiller) is installed correctly according to the drawings, Commissioning verifies that the chiller, the cooling tower, the pumps, the building automation system, and the air handlers all communicate and function interactively as a unified system under various loads and failure scenarios.

The Commissioning Authority (CxA)

The Commissioning Authority (CxA) leads the process. To ensure objectivity and prevent conflicts of interest, the CxA should ideally be an independent, third-party firm hired directly by the Owner. While the CM often helps procure and manage the CxA on behalf of the owner, the CxA should not be a subcontractor to the General Contractor whose work they are verifying, nor should they be the Design Engineer who designed the systems.

The Commissioning Process by Phase

A common misconception is that commissioning is an activity that happens at the very end of construction. In reality, comprehensive commissioning is a lifecycle process.

1. Pre-Design Phase

• Develop the OPR: The CxA assists the owner in defining the Owner's Project Requirements. This document captures the functional requirements of the facility (e.g., "The data center must maintain 68°F +/- 2°F at all times with N+1 redundancy").
• Develop Initial Cx Plan: Outlines the scope of commissioning, budget, and team roles.

2. Design Phase

• Review the Basis of Design (BOD): The CxA reviews the design team's BOD to ensure it aligns with the OPR.
• Design Reviews: The CxA conducts focused reviews of the design documents at various milestones (e.g., 50%, 90% CDs) specifically looking for system integration issues, maintainability, and ability to test.
• Draft Commissioning Specifications: The CxA writes the Cx specifications that will be included in the contractor's bid documents, detailing the contractor's responsibilities during testing.

3. Construction Phase

• Submittal Review: The CxA reviews concurrent with the design team, focusing on system performance and O&M data.
• Pre-Functional Checklists (PFCs): The CxA issues checklists that the contractor must complete to verify equipment is physically installed correctly and ready for power.
• Site Observations: The CxA visits the site to verify installation quality and maintainability (e.g., ensuring clearance exists to replace filters).

4. Acceptance Phase (Testing)

• Functional Performance Testing (FPT): This is the core of field commissioning. The contractor operates the equipment while the CxA directs and witnesses the tests. Systems are tested under full load, partial load, and failure modes (e.g., pulling the plug on primary power to watch the generator and transfer switch sequence correctly).
• O&M Manual Review: Verifying the manuals are complete and accurate.
• Training Verification: Ensuring the owner's facility staff are properly trained by the contractors on how to operate the systems.

5. Post-Acceptance (Occupancy) Phase

• Seasonal Testing: Some systems cannot be fully tested until the appropriate season (e.g., testing the heating system during the peak of winter).
• End of Warranty Review: The CxA returns typically 10 months into the 12-month warranty period to interview facility staff, review system operations, and identify any issues the contractor must fix before the warranty expires.
• Final Commissioning Report: The comprehensive log of all testing, issues resolved, and remaining items.

Systems Typically Commissioned

While theoretically any building element can be commissioned (including building envelope commissioning, or BECx), the most commonly commissioned systems are highly dynamic and interactive:

• HVAC (Heating, Ventilation, and Air Conditioning)
• Building Automation Systems (BAS) / Controls
• Electrical power and lighting controls
• Emergency power (generators, ATS)
• Fire and life safety systems
• Plumbing and domestic water

Types of Commissioning

The terminology changes based on the building's age and history:

• New Construction Commissioning (NCCx): The process applied to a new building from design through occupancy.
• Retro-Commissioning (RCx): The application of the commissioning process to an existing building that has never been commissioned before. The goal is to optimize operations and resolve systemic issues that have existed since construction.
• Re-Commissioning (ReCx): The application of the commissioning process to an existing building that was previously commissioned. This is essentially a "tune-up" to bring the building back to its original commissioned performance baseline after years of operational drift.
• Continuous Commissioning (CCx): Utilizing permanent metering and software to constantly monitor system performance and detect anomalies in real-time.